A rectangle has its longer side 2 cm greater than its shorter side. Its area is 80 cm2. Find the perimeter of the rectangle (in cm).
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 36
Area of a rectangle \(=\) length \(\times\) breadth; the two sides are written with one unknown and the quadratic is solved, keeping only the positive root.
Let the shorter side be x cm; the longer side is \((x+2)\) cm
\(x(x+2)=80\), that is, \(x^2+2x-80=0\)
\((x+10)(x-8)=0\), so \(x=8\) (a side cannot be −10)
Sides 8 cm and 10 cm; perimeter \(=2(8+10)=36\) cm